Mall shop cassette dripped late: hose loose at the pump

A Jurong East mall shop had a ceiling cassette that stayed dry early, then started dripping late in the day. The timing mattered. A leak that appears only after long retail runtime points first to drainage load and pump response, not an instant tray failure.

By Team Snowflake | Updated 28 Jul 2026

Case summary

Mitsubishi Electric Cassette8 years oldRetailJurong East, Singapore

Concern: Staff worried the cassette tray had cracked because water was landing near display stock after the evening crowd.
Found: Discharge hose partially detached from the pump outlet, worked loose by hours of compressor vibration
Key check: Ran the unit for an extended stretch and checked the discharge hose connection at the pump outlet before blaming the tray
Result: The cassette ran through a longer test without dripping. The shop avoided ceiling teardown work and had a clearer maintenance cue: if a drip returns late in the day, check the discharge hose connection before assuming the tray failed.

What we were told

The shop team saw water near the indoor unit only after the aircon had run for most of the day. It did not drip during opening checks. The wet patch was close to display stock, so staff wanted the leak settled without guessing at a ceiling teardown.

What we checked

The timing came first. A cracked tray usually leaks whenever water reaches the damaged spot, but a hose connection loosened by vibration can hold up fine on a short run and only leak once it runs for hours. We checked the pan, the pump outlet, the discharge hose inside the ceiling void, and the outlet flow after running the unit long enough to mimic a full retail day.

The tray surface and visible cassette panel did not show a crack.
The pump cleared water normally during a short test run.
Inside the ceiling void, the discharge hose sat loosely over the pump outlet instead of gripping it tightly.
After a longer run, water reached that loose joint and escaped there before it reached the discharge line.

What we found

Inside the ceiling void, the discharge hose had partially slipped off the pump outlet. On a short test run this made no visible difference, since the loose joint still passed enough water to clear normally. Once the compressor ran for hours at a stretch, sustained vibration worked the hose further off the outlet, and enough water escaped at that joint to drip through the panel edge. The pattern only showed up late in the day because it needed sustained runtime to open the gap wide enough to leak, not a cracked pan or a refrigerant issue.

What fixed it

We pushed the discharge hose fully back onto the pump outlet and secured it so vibration could not work it loose again. We ran the cassette through an extended test to confirm the joint held under sustained operation, not just a short check. We did not quote pump or tray replacement, because the pump itself was clearing water normally throughout. The advice was to have the hose connection checked specifically after any work that disturbs the ceiling void.

Outcome

The cassette ran through a longer test without dripping. The shop avoided ceiling teardown work and had a clearer maintenance cue: if a drip returns late in the day, check the discharge hose connection before assuming the tray failed.

What this case teaches us

Late retail drips need runtime and drainage checked together

If a cassette stays dry early and drips late, the drain system needs a longer water-load test.
Retail units run for many hours, so a hose connection loosened by vibration can look fine during a short morning check.
Before approving tray work, ask whether the hose connection at the pump outlet was tested after a full day of runtime, not just a short check.

Questions this case answers

Shop cassette only drips late in the day: why not in the morning?

Because the fault needed hours of running to open up. A cracked tray leaks whenever water reaches the damaged spot, so a drip that waits until evening is telling you something else. Here the discharge hose sat loosely over the pump outlet, and sustained compressor vibration worked it further off as the day went on.

Does a dripping cassette mean the tray has cracked?

Not on its own. The tray surface and the visible panel showed no crack on this Jurong East shop unit, and the pump cleared water normally. Timing is what separates a tray fault from a drainage fault, so it is worth noting when the water appears before anyone opens a ceiling.

Can a short test run miss a drainage leak?

Easily. A loose joint still passes enough water to look fine over a brief check, which is why an opening-hours inspection came up clean. Only after a longer run, matching a full retail day, did water reach that joint and escape there before it made the discharge line.

What should be checked after any work inside the ceiling void?

The discharge hose connection at the pump outlet. It is the joint most easily disturbed and the one vibration works loose over time. We pushed it fully back on and secured it, then ran an extended test to confirm it held under sustained operation rather than over a short cycle.

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